Moonrise and moonset calculator – moon phase and direction on a map

When does the moon rise tonight, where on the horizon will the full moon come up behind the church tower, and is there any moonlight for the night hike next Saturday? The moon is harder to keep track of than the sun: it rises on average about 50 minutes later each day, some days it does not rise or set at all, its phase changes through a 29.5-day cycle, and its rising point swings north and south of east much faster than the sun's. This tool works it all out for any place on Earth and any date and time. Pick a point and the map gets a light blue line towards moonrise, a dark blue line towards moonset and a purple line towards the moon at the chosen time, with the moon's path across the sky drawn as a curve: the sky seen from above, with the point straight overhead in the middle and the dashed circle as the horizon. The panel gives the phase by name and the share of the disc that is lit, the age of the moon in days, its elevation, azimuth and distance from you, moonrise, moonset and the moment it stands highest, and the dates and times of the next new moon, first quarter, full moon and last quarter. A small picture shows the moon the way it looks in the sky from that place, tilted as it really is: low in the tropics a crescent lies on its back like a boat. Every time is given in the place's own time zone, and a whole month of moonrise and moonset times can be downloaded as CSV.

How to use it

1. Click the map, search a town or city, paste coordinates or press "Use my location".
2. Choose a date, then drag the time slider or press Now to see the moon's phase, elevation, azimuth and distance at that moment.
3. Read moonrise, moonset, the culmination and the next phases in the panel; the lines on the map show the directions.
4. Download the whole month as CSV, the lines as GeoJSON or KML, or copy the share link.

How accurate is it?

How the moon's position is calculated

The moon's position comes from chapter 47 of Jean Meeus' Astronomical Algorithms, a shortened version of the ELP-2000/82 lunar theory with 60 periodic terms for the longitude and distance and 60 for the latitude, plus nutation and the sidereal time. Because the moon is so close, its direction depends on where you stand on the Earth by up to about one degree, twice its width, so the tool corrects for your position (parallax). We tested it against PyEphem, an astronomical library: on 400 random places and moments between 2020 and 2031 the elevation and azimuth differed by at most 0.003° and the lit share by at most 0.3 percentage points.

How moonrise and moonset are found

Moonrise and moonset are the moments the top edge of the moon touches a flat horizon, with 34′ for the bending of light in the atmosphere, the convention almanacs use. The tool follows the moon's elevation through the whole local day and finds every crossing to the second, so days with no moonrise or no moonset come out without special cases. On 400 random days between 60° S and 60° N, moonrise, moonset and the meridian transit agreed with PyEphem within about one second. The instants of new moon, full moon and the quarters agree within two minutes.

What the calculation leaves out

The formulas assume a flat, sea-level horizon and a standard atmosphere. Hills, buildings and trees hide the moon until later than the calculated moonrise, a high viewpoint sees it earlier, and unusual temperatures bend the light more or less, which moves moonrise by a minute or two at mid latitudes and by much more near the poles. The elevation shown is the apparent one, including refraction. Whether you can actually see the moon also depends on the clouds and, for a thin crescent, on how bright the sky still is.

Good to know

Some days have no moonrise

The moon rises on average about 50 minutes later each day, so roughly once a month the moonrise slips past midnight and one calendar day has no moonrise at all; the same happens to the moonset on another day. The panel then says so, and the moonrise comes just after midnight the next day. Near the poles the moon can stay up or down for several days in a row.

The full moon is a moment, not a night

New moon, full moon and the quarters are instants, when the moon is exactly 0°, 180°, 90° or 270° ahead of the sun along the ecliptic, and they happen at the same moment everywhere. In your time zone that moment can fall on a different calendar date than in a newspaper from another country. The tool names the phase from the moon's position at your chosen time: within about half a day of an exact phase it shows that phase, otherwise the crescent or gibbous moon in between.

The lit share is not the phase

At first and last quarter half the disc is lit, but the lit share then changes fastest, by about 12 percentage points a day; near new and full moon it changes slowly. A moon that looks full to the eye can be only 97 % lit. The age in days counts from the last new moon; a whole cycle, the synodic month, lasts 29.53 days on average but varies by more than half a day.